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METHOD AND APPARATUS FOR COOLING AND LUBRICATING GAS TURBINE BEARINGSOrigmal Filed Feb. 25, 1956 ATTORNEYS United States Patent 25 227 METHODAND APPARATUS FOR COOLING AND LUBRICATING GAS TURBINE BEARINGS WillardE. Buck, P.O. Box 357, Boulder, Colo. Original No. 2,886,285, dated May12, 1959, Ser. No. 567,148, Feb. 23, 1956. Application for reissue Jan.11, 1960, Ser. No. 1,832

7 Claims. (Cl. 8874) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

This invention relates to air-cooled bearings; and more particularly, toa method and apparatus for air-cooling bearings of high-speed turbines.

In recent years a number of high-speed rotating systems have beendeveloped which attain rotational speeds as high as 15,000 r.p.s. andare being used in devices such as centrifuges and rotating mirrorcameras. Rotating mirror cameras, in particular, have been made whichwill take pictures at the rate of 3,500,000 frames per second utilizinga high-speed turbine-driven rotating mirror.

The design of a turbine which would achieve these tret mendousrotational speeds involved the solution of a number of problems whichwere substantially unheard of in connection with conventional machinedesign. Turbines had to be developed which would spin a small polishedsteel mirror up to the bursting strength of the steel used.

One of the most difiicult problems that had to be solved was the designof bearings which would withstand these rotational speeds and a coolingsystem which could be depended upon to keep the bearings cool duringoperation of the turbine. It was found that high-speed ball hearingswere unsatisfactory and that pressurized-air bearings could not be usedat speeds above 3000 r.p.s. without bearing failure. Therefore,liquid-lubricated bearings were found to be the only satisfactory typethat would withstand the strain and heat without failing. Theseliquid-lubricated bearings were generally made of silver because of itsexcellent heat conductivity and the oil used for lubrication wascontinually circulated around the bearing at the rate of approximately0.3 gallon per minute.

It has now been found, however, in accordance with the present inventionthat the design of high-speed turbines can be much improved andsimplified through the us of a novel method and apparatus forair-cooling the hearing which eliminates the necessity for continuouscirculation of the oil around the bearing. More specifically, thecompressed air, hydrogen, helium or other gas utilized as a drivingforce for the turbine Wheel is exhausted into an exhaust cavity adjacentthe sealed liquid-lubricated bearing where it becomes quite cold due toexpansion and, therefore, can be used to carry the heat away from thebearing out through the exhaust system. The degree of cooling attainedby the aforementioned system is such that the lubricating oil need notbe circulated around the hearing and all that is required is to maintainthe lubricant under suflicient pressure to prevent the oil-film whirleifect from taking place due to the rotational speed of the mirrorshaft.

It is, therefore, the principal object of the present invention toprovide a novel air-cooling method and apparatus for cooling theliquid-lubricated bearings of high-speed turbines.

Another object of the invention is to provide a greatly simplifiedlubrication system for the bearings of a highspeed turbine.

A further object of the invention is to provide a highspeed turbinewhich does not require the conventional oilcirculation system to provideadequate cooling for the bearings.

Other objects will be in part apparent and in part pointed outspecifically hereinafter in connection with the description of thedrawing which follows, and in which:

FIGURE 1 is a longitudinal section of a high-speed rotating-mirrorturbine employing the novel air-cooled liq- Hid-lubricated bearings ofthe present invention.

FIGURE 2 is a transverse section taken along line 22 of FIGURE 1;

FIGURE 3 is a transverse section taken along line 33 of FIGURE 1;

FIGURE 4 is a longitudinal section taken along line 4% of FIGURE 2;

FIGURE 5 is a longitudinal section taken along line 55 of FIGURE 1;

FIGURE 6 is an enlarged fragmentary longitudinal section showing thebearing;

FIGURE 7 is an enlarged fragmentary longitudinal section taken alongline 77 of FIGURE 6;

FIGURE 8 is a view showing the end plate used to retain the bearing inplace within the main housing of the turbine;

FIGURE 9 is an enlarged elevation of the bearing, and,

FIGURE 10 is a section of the bearing taken along line 1010 of FIGURE 9.7

Referring now in particular to FIGURES 1 through 5 inclusive, of thedrawing, it will be seen that the turbine is mounted in a main housing12 having an axial opening 14, defining a hollow interior extending fromend to end thereof, which receives the various elements of the turbine.Mirror 16 is inserted within the axial opening 14 adjacent opening 18 inthe side of the main housing communicating with a central chamber andwhich admits light to the polished face of the mirror mounted within thecentral chamber to be reflected onto the surface of the film. The mirroris formed of steel or other high strength material and is provided withan integral mirror shaft 20 and journals 22 at each end.

Turbine housing elements 24 are positioned within the main housingadjacent each end of the mirror and are provided with an outer annularair passage 26 and a pinrality of radial air passages 28 whichinterconnect the outer annular air passage with an inner annular airpassage 30 formed between the turbine housing elements and elements 32together defining an intake cavity which contain the stationary bladesor nozzles 34 of the turbine. The turbine Wheel or rotor 36' is attachedto mirror shaft 20 for conjoint rotation and is provided with turbineblades 38 positioned to receive air from nozzles.

The main housing 12 contains a main compressed air line 40 connected bysuitable fittings 42 to a source of compressed air or other gas, notshown. It should be mentioned that although the various elements of theturbine and operation thereof will be described in connection withcompressed air as an operating medium, it is to be understood that othergases such as hydrogen and helium can be used and are enecessary forultra high-speed operation.

The outer annular air passage of the turbine-housing elements isconnected into main airline 40 by air intake ports 44. The high pressureair is introduced into the turbine through the main compressed air line40, passes from the main line into the outer annular air passages 26through air intake ports 44, then passes into the inner annular airpassages 30 through the radial air passages 28', moves through thenozzles 34 against blades 38 of the turbine wheel and expands intoexhaust cavity 46 which together with the intake cavity defines a gaschamber. The rapid expansion of the air in the exhaust cavity after itleaves the turbine blades causes the air to become quite cold before itpasses over the surface of bearing housing 48. The bearing housings 48fit into the ends of the axial opening 14 in the main housing and areretained in place by end plates 50 and 50a which are removably attachedto the housing by bolts 52. The bearings 54 fit into the bearing housingand are held in place by fingers 56 which project inwardly against theinner conical surface 58 of the bearing from tubular portions 60 of theend plates. Journals 22 of the mirror shaft rotate within the bearings,as shown.

Oil for lubricating the bearings is supplied by means of a closed,pressurized oil system which will now be described. An oil reservoir 62is provided at one end of the main housing and the oil level therein ismaintained such that the entry to oil outlet tube 64 will remaincovered. The oil is maintained under pressure at all times duringoperation of the turbine by by-pass air connection 66 which takes airfrom the main compressed air line into the oil reservoir at a pointabove the oil level. The oil outlet tube 64 interconnects the oilreservoir with main oil line 68, shown most clearly in FIGURE 5. Againwith reference to FIGURE it will be seen that the main oil line feedsoil into oil passages 70 and into the oil chamber to one side of thebearing housing through oil passages 72 in the main housing. In thismanner the oil is introduced into annular cavity 74 between the innersurface of the bearing housing and the outer surface of the tubularportion 60 of the end plate. The high-speed rotational movement of thejournal within the bearing causes the oil to move through opening 76 inthe tubular portion 60 of the end plate, into the space within the oilchamber between the bearing and the bearing housing, and between thebearing and journal. Although the oil is not circulating in the sense ofa fresh supply being constantly introduced into the bearings it iscontinually in motion due to the swirling motion imparted thereto byrotation of the journal. The oil is maintained under pressure at alltimes during operation of the turbine in order to prevent the oilwhirleffect from throwing the oil away from the journal in the well-knownmanner. The bearing, bearing housing and end plate are, of course,provided with suitable O-ring seals, as shown, to seal and maintainpressure within the liquid-lubricated bearing unit. Fingers 56 carriedby the tubular portion 60 of the end plate maintain the bearing 54 incorrect spaced relation to the bearing housing when no oil pressure isexerted thereon.

Exhaust cavity 46, shown most clearly in FIGURE 2, at the front or oilreservoir end of the turbine exhausts through exhaustpassages 78 in themain housing. The exhaust cavity at the rear end of the turbine exhauststhrough exhaust passages 80, as shown most clearly in FIGURE 4. All ofthe exhaust passages open into chamber 82 which is open to theatmosphere through opening 84 therein.

The turbine housing element 24 is provided with suitable O-rings, asshown, to prevent leakage of air into the mirror cavity and ismaintained in place within the main housing by pins 86 and set screws88. End plate 50a on the front end of turbine is slightly modified toprovide an axial opening 90 to receive shaft '92 for rotational movementtherein. Shaft 92 is journaled for rotation in tubular element 94 whichpasses through the oil reservoir and is pressure-sealed therein. Shaft92 is also mounted for longitudinal slidable movement in the tubularelement and the end plate 50a and is maintained in retracted position bycompression spring 96 acting between the end plate and stop 98 of theshaft. The rear end of the shaft is provided with a tongue 100 adaptedto fit into the notchedend 102 of the front journal. The sole functionof shaft 92 is to permit manual rotation of the mirror by rotating knob104 while the shaft is interlocked with the mirror.

Referring now in particular to FIGURES 6 and 7 of the drawing, it willbe seen that a space 106 is provided between the outer conical surface108 of the bearing 54 and the inner conical surface 110 of the bearinghousing 48 to provide for the movement of oil therebetween. Wall 112.ofthe bearing housing is relatively thin to provide for rapid heattransfer between the bearing and exhaust air cavity 46. The cold exhaustair from the turbine blades passing over the outer surface of thebearing housing conducts the heat away from the bearing in the exhaustair and eliminates the necessity for continuous circulation of thelubricating oil around the bearing. As already men- 5 tioned, however,the lubricating oil is in motion within the bearing housing due to theswirling effect caused by rotation of the journal. This effect maintainsthe lubricating oil at a relatively constant temperature and therelatively cold exhaust air has been found adequate to maintain thebearing quite cool even though the turbine is operated at speeds wellabove 10,000 r.p.s.

The particular bearing design shown in FIGURES 9 and 10 is conducive toexcellent heat transfer because of the large surface area exposed to thelubricant. The particular bearing design, shown most clearly in FIGURES9 and 10 comprises tubular portion 114 terminating in a flaring portion116 which is relatively thin and exposes large conical surfaces 58 and108 to the oil.

End plate 50a, shown in FIGURE 8, is provided with tubular portion 60which extends into the beating housing in concentric spaced relationthereto and the fingers '56 extending from the tubular portion engagethe inner conical surface 58 of the bearing and hold it in sealed spacedrelation with respect to the bearing housing.

From the foregoing description of the invention in connection with ahigh-speed rotating-mirror turbine it will be seen that the many usefulobjects for which the novel method and apparatus for air-cooling aliquid-lubricated A bearing were designed, have been achieved; andtherefore,

I claim:

[1. In a turbine, a housing having a hollow interior, means including ahearing within the housing dividing the 7 interior thereof into a gaschamber and an oil chamber,

means including a shaft having journals journaled for rotation withinthe bearing, said bearing and said shaft coacting to seal the gaschamber from the oil chamber, a turbine wheel mounted on the shaft inposition to divide the gas chamber into an intake cavity and an exhaustcavity, the latter of which is in heat-exchange relation to the oilchamber, and nozzle means within the intake cavity located to receivegas from said intake cavity and direct it through the turbine wheel tothe exhaust cavity to effect rotation of the shaft and cool any oil inthe oil chamber upon expansion of said gas] .2. In a turbine, a housinghaving a hollow interior, means including a pair of bearings arranged inspaced relation within the housing each of said bearings dividing adifferent portion of the interior of said housing into a gas chamber andoil chamber, means including a shaft having journals journaled forrotation within the bearings, said bearings and said shaft coacting toseal each gas chamber from its respective oil chamber, a turbine wheelmounted on the shaft in position to divide each gas chamber into anintake cavity and an exhaust cavity,

5 the latter of which is in heat-exchange relation to each oil chamber,and nozzle means within the intake cavity located to receive gas fromsaid intake cavity and direct it through the turbine wheels to theexhaust cavities to effect rotation of the shaft and cool any oil in theoil chambers upon expansion of said gas.

3. In a turbine, a housing having a hollow interior, spaced bearinghousings mounted within the housing dividing the interior thereof into acentral chamber and oil A chambers on opposite ends thereof, shaftbearings within the bearing housings, a shaft having journals journaledfor rotation within the shaft bearings, said shaft and said bearingscoacting to seal the oil chambers from the central chamber, a mirrorformed intermediate the ends of the shaft for rotation within thecentral chamber, means within the housing enclosing the shaft onopposite ends of the mirror and forming a gas chamber adjacent eachoil-chamber, turbine wheels mounted on the shaft in position to divideeach gas chamber into an intake cavity and an exhaust cavity, the latterof which is in heatexchange relationship to the adjacent oil cavity, and

nozzles positioned within the intake cavities located to direct gasthrough the turbine Wheels to the exhaust cavities to efiect rotation ofthe mirror and cool any oil in the oil chambers upon expansion of saidgas within said gas chambers.

4. The turbine as set forth in claim 3 in which the housing includes anoil reservoir with conduit means connected to deliver oil to the oilchambers, and a source of gas under pressure connected into the intakecavities and also connected into the oil reservoir to pressurize the oilaround the bearings.

5. The turbine as set forth in claim 3 in which the central chamber isopen through the housing to expose the mirror and the exhaust cavitiesare open to the atmosphere.

6. In a turbine, a main cylindrical housing having a hollow interiorcomprising an axial cylindrical bore, bearing means including a pair ofbearings arranged in spaced relation to each other within the housing,each of said bearings being supported by a bearing housing located insaid cylindrical bore, and each of said bearings and bearing housingsdividing a difierent portion of the interior of said main housing into agas chamber and an oil chamber, means including a shaft having journalsjournaled for rotation within the bearings, said bearings, said bearinghousings, and said shaft coacting to seal each gas chamber from itsrespective oil chamber, a turbine wheel mounted on the shaft in positionto divide each gas chamber into an air intake cavity and an exhaustcavity, each exhaust cavity of which is in heat exchange relation toeach oil chamber, respectively, an inner housing member within eachintake cavity and having nozzle means and located to receive gas fromsaid intake cavity through an outer annular air passage directing air toall of said nozzle means, said nozzle means being located to direct saidgas through the turbine wheels to the exhaust cavities, respectively, toefiect rotation of the shaft and cool any oil in the oil chambers uponexpansion of said gas in the exhaust cavities.

7. In an air driven turbine, the combination of a cylindrical mainhousing having a through bore of cylindrical shape, said bore having acircular closure for one end provided with threaded means for securingthe closure to the main housing, sealing one end of the main housing,said housing having a radially extending inlet port communicating withan inlet conduit, a cylindrical turbine inner housing element fitting inthe other end of said through bore and closing the other end of saidbore, means carried by the said main housing for securing said innerturbine housing element against rotation and longitudinal motion in saidbore, said inner turbine housing having a circular bore for passing anaxial shaft, a shaft in said circular bore and extending from said innerturbine housing, said inner turbine housing having an outer annular airpassage communicating with said inlet, a bearing housing having acylindrical body mounted in said cylindrical bore in the main housing,and said body having a bore, a bearing member in said latter bore, saidshaft having a reduced cylindrical end and an annular shoulder, saidreduced end being received in said bearing member, and said annularshoulder engaging an annular face of said bearing member, said circularclosure supporting a tubular portion engaging said bearing member andsecuring the annular face of the bearing member against the annularshoulder on the shaft, a turbine rotor carried by the shaft and providedwith turbine blades to receive air to drive the turbine, saidcylindrical bore in said main housing having an exhaust cavity receivingair from the turbine blades, said annular air passage in said innerturbine housing communicating with stationary blades on an inner turbineelement forming nozzles directing air against the blades of the rotor.

8. A fluid operated turbine comprising a round housing having a throughbore and an annular expansion chamber, a bearing housing in each end ofsaid bore, a bearing mounted in each of said bearing housings, a shaftrotatably mounted in both of said bearings, a rotor having an axial borereceiving and attached to said shaft, said rotor ha ving turbine bladesto receive air from nozzles to efiect rotation of the shaft, a turbinehousing having a bore secured in said through bore and having an annularfluid distributing channel formed in its periphery and opening radiallyoutward, said round housing having a radially extending inlet portcommunicating with said channel and an axially extending inlet conduitextending to said port, a stator element having a cylindrical borereceiving the shaft and mounted in said bore of said turbine housing,said stator element having a reduced portion about said shaft forming incooperation with the turbine housing an annular air distribution channeland said stator element having nozzles on its periphery for directingfluid flowing from said annular air distribution channel against theblades of the rotor to drive the rotor, said turbine housing having aplurality of apertures providing communication between said annularfluid distributing channel and said annular air distribution channel,said rotor discharging fluid into said annular expansion chamber andsaid expansion chamber having an enlarged lateral outlet for dischargingthe exhaust fluid, an end closure for one end of said bore having anopening and a spring pressed plunger extending through said opening andhaving a driving rib on its end for engaging in a complementary slot inthe and of said shaft, a stop carried by said plunger and a spring aboutsaid plunger acting on said stop to urge the plunger outward out ofengagement with the shaft, and a manual member on the end of saidplunger for use in pressing the plunger inward to engage the shaft androtate the shaft manually.

References Cited in the file of this patent or the original patentUNITED STATES PATENTS 887,380 Dake May 12, 1908 900,806 Watkins Oct. 13,1908 972,327 Brien Oct. 11, 1910 1,310,674 Sherbondy July 22, 19221,603,927 Taylor et al Oct. 19, 1926 1,624,529 Burlington et al. Apr.12, 1927 1,672,721 Junggren June 5, 1928 1,708,306 Giesler Apr. 9, 19291,878,747 Youngblood Sept. 20, 1932 1,889,554 Kennedy Nov. 29, 19322,098,121 Wilkinson Nov. 2, 1937 2,323,725 OBrien July 6, 1943 2,435,042Iohansson Ian. 27, 1948 2,483,654 Magdeburger Oct. 4, 1949 2,527,446Jenks et al. Oct. 24, 1950 2,709,567 Wood May 31, 1955 2,759,700Wheatley Aug. 21, 1956 2,910,005 Angell et al. Oct. 27, 1959 2,991,926Diefenderfer July 11, 1961 FOREIGN PATENTS 27,045 Great Britain of 190425,910 Great Britain of 1907 71,844 Norway Mar. 24, 1947

